1. Field of the Invention
The present invention relates to a gas turbine combustor which can suppress the amount of nitrogen oxides (hereinafter referred to as “NOx”) discharged from the combustor, even when the combustor is operated with a relatively high load or intensity.
2. Background Art
For the gas turbine apparatus, a highly strict environmental standard is established on the composition of exhaust gas discharged from the turbine upon the operation thereof. Especially, in this standard, substantial reduction of the discharge amount of NOx contained in the exhaust gas is required. In the past, as one approach for reducing the discharge amount of NOx in regard to the gas turbine apparatus, a method for lowering the temperature of the combustion flame by injecting water or steam into the combustion chamber has been employed. With this method, however, the thermal efficiency of the apparatus may tend to be degraded, and/or life span of the apparatus may be shortened due to corrosion of the turbine caused by poor quality of the water used. In order to solve such problems, one gas turbine apparatus employing a DLE (Dry Low Emission) type combustor, intended for reducing the discharge amount of NOx, without using the water and/or steam, has been developed in recent years. The gas turbine apparatus of this type includes an additional pre-mixing type supplemental burner provided to a downstream portion of a combustor cylinder of the DLE combustor. With this configuration, fuel can be further supplied by the supplemental burner, in a state in which the fuel that is not yet combusted is no longer discharged or detected from an upstream region of the combustor. In this way, the amount of NOx discharged from the turbine can be substantially reduced (see Patent Documents 1, 2).